Went into Windows Defender to Allow apps to communicate thru Windows Defender and they are both there WB 12 and WB14
checked for Privat but deleted them in Defender and uploaded again - but same thing.

Not Found
The requested URL /blankpagewithscript1.php was not found on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

Not Found (working now did Selected page only)
The requested URL /blankpagewithscript2.php was not found on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

Not Found
The requested URL /blankpage.php was not found on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

I think that somewhere in your project you have added the code. To be able to help you I need your project.
But please understand that for me it may also take a lot of time to figure out where it was added.

"In other words: Uploading the whole thing: nothing - uploading one page at a time: it works (checkboxes are there)."

5 days ago I got the Internet exception error 12111. (never had it before)
Uploading the whole thing: Internet exception error 12111. Closed the project - opened it again and
it worked uploading one page at a time and then it stopped uploading again - got the error message.

As mentioned I bought a full new version of 14.1.1 as a thank you for offering to go thru
the whole site (which has a lot of pages) but I think you don't need to.

Have uploaded pages and used it many times and
everything seems great now - however after going thru the pc's step by step - I do think it was another software that was trying to load
and run itself and did that all the time - that caused the problems. That software was taken out and pc's cleaned and for the past days
everything has been running smoothly.

Something must have gone wrong when installing WB 14.1.1 update because of the other software (as mentioned above)
was trying to load and install itself all the time.

Thanks Pablo for great help - you're a fantastic software developer!!!